This invention relates generally to a topsheet used in a body fluid absorbent garment such as a disposable diaper, sanitary napkin or the like.
Japanese Patent Application Publication (Kokoku) No. Sho57-17081 discloses a topsheet comprising a plastic film formed with a plurality of tapered liquid-passages. A smooth upper surface of the film is intended to contact a wearer's skin. The liquid-passages open in the upper surface of the film and extend downward from the upper surface toward the lower surface of the film.
Japanese Laid-Open Patent Application (Kokai) No. Hei4-82977 discloses a topsheet comprising a first pair of ribs extending parallel to each other, another pair of ribs extending parallel to each other and orthogonally to the first pair, and air-permeable and moisture-permeable openings formed in regions defined by the two pairs of ribs.
The liquid-passages and the openings provided in the foregoing topsheet are certainly effective to transfer discharged body fluids to a liquid-absorbent core directly underlying the topsheet.
However, the topsheet disclosed in the Japanese Patent Application Publication No. Sho57-17081 has its upper surface except the openings of the respective liquid-passages in direct contact with the wearer's skin. The topsheet disclosed in the Japanese Laid-Open Patent Application No. Hei4-82977 has the ribs each presenting a cross-sectional shape curved so as to widen toward an absorbent core immediately underlying the ribs. Such a topsheet contacts the wearer's skin not only crests of the respective ribs but also portions adjacent the crests.
With these known topsheets, an area over which the topsheet contacts the wearer's skin increases as an area occupied by the openings in the upper surface (opening area ratio) decreases. A garment using such topsheet often causes stuffiness and/or eruption due to wearing the garment.